IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676, p-ISSN: 2320-3331, Volume 15, Issue 2 Ser. I (Mar – Apr 2020), PP 26-35 www.iosrjournals.org DOI: 10.9790/1676-1502012635 www.iosrjournals.org 26 | Page Soil Resistivity Analysis and Earth Electrode Resistance Determination P.D.R Dilushani 1 , W.R.N Nawodani 2 , Tharangika Bambaravanage 3 and K.A.C Udayakumar 4 Department of Electrical and Computer Engineering, The Open University of SriLanka 1,2,4 , Division of Electrical, Electronics and Telecommunication Engineering Technology, Institute of Technology University of Moratuwa 3 Abstract—A good grounding system is very important not only for safety reasons but also for preventing damages to industrial plants and equipment. At present, an earth electrode of the length 3.5 feet is in use in Sri Lanka, for domestic installations, which is readily available in the market and much popular among consumers and electricians. This may not comply with the maximum allowable earth resistance for the TT systems. Earth resistance depends on the earth resistivity, value of which depends on the soil structure of the location concerned. The intention of this work is to investigate the actual resistance of the said earth electrode’s resistance at an identified location. Determination of soil resistivity is one of the key areas of this work, considering the earth as a homogeneous, two-layer and multilayer model for an identified soil entity, comprises with different type of soil layers. For each of these models the earth resistivity has been determined. CDEGS software has been used to determine resistivity of two -layer and multi-layer soil model. Voltage distribution on the surface of the earth has also been analyzed in the research. The actual values and values taken from analytical expressions have been compared with the standard value of the earth electrodes resistance Index Terms—Grounding system, earth electrode, multilayer earth model, soil resistivity --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 27-02-2020 Date of Acceptance: 12-03-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction A good grounding system is very important not only for safety reasons but also for preventing damages to industrial plants and equipment. A grounding system with high ground resistance provides unsafe path for a fault current, while making likelihood of severe injury to human beings and increased risk of equipment failure. If a fault current does not find any path to pass to the ground through a properly designed grounding system, its alternative path may be through some sophisticated equipment or in the worst case, through a human body. A high chance of Instrumentation errors and harmonic distortions in any electrical system is possible due to poor grounding systems [1], [2], [3]. To ensure sufficient electrical protection for humans and equipment available, it is very important to maintain the grounding resistance as per the specified limits which is 10 Ω or less for domestic installations. Sri Lanka, this is implemented with long term experience or through trial and error techniques. This may lead to over-design or under design grounding systems [2]. Over-design system brings Fig. 1.Wenner 4-pole method can be used to measure earth resistance of a given location for homogeneous soil environment waste of material and labor cost and under-design system causes situations with safety issues [2]. Therefore, it has become a necessity to evaluate the effectiveness of popular/ common earthing methodologies in order to come-up with an optimum solution.